Thin-film EL devices have advantage in that light-emitting devices can be fabricated on large-area substrates by film-forming techniques such as evaporation and sputtering. Devices fabricated in this manner can be assembled into a flat panel display. The flat panel display is composed of a plurality of thin-film EL devices in the form of a matrix array and a circuit for driving them. The conventional structure of each thin-film EL device is described below with reference to FIG. 5.
As shown in FIG. 5, the thin-film EL device has a dual dielectric structure which comprises a glass substrate 11 that is overlaid, in this order, with a lower electrode 12 that serves as one electrode for the matrix (X axis electrode), a first dielectric layer 13, a luminescent layer 14, a second dielectric layer 15, and an upper electrode 16 that serves as the other matrix electrode (Y axis electrode).
In order to operate the flat panel display having the above matrix structure, an A.C. electric field with a voltage of from 200 to 250 V is applied to the luminescent layer 14 between the lower electrode 12 and the upper electrode 16, whereupon light is emitted from the luminescent layer 14. If the number of the electrodes on the X axis is n, and the number of electrodes on the Y axis is m in the flat panel display, (m+n) of driver circuits (not shown) are necessary to drive the display. In other words, a plurality of ICs (not shown) are required to drive the display.
However, as already mentioned, the voltage required to trigger light emission from the luminescent layer 14 in the thin-film EL device having the structure described above is as high as 200 to 250 V and this requires that the driving ICs serving as switching elements for the respective thin-film EL devices should be capable of withstanding such high voltage. Since special processes are required to fabricate such driving ICs having high withstand voltage, they are expensive and this leads to an increase in the production cost of flat panel displays.